With the progress of the times, the internet and mobile communication network provide massive functions and applications. A user not only can use a mobile terminal to perform conventional applications, such as use a smart phone to answer a call or call somebody up, but also can use the mobile terminal to browse a webpage, transmit a picture or play a game and so on.
With the increasing usage frequency of the mobile terminal, it is required to charge the mobile terminal frequently. Further, with the user's requirement on the charging speed, some mobile terminals do not monitor the charging current and can accept a bigger charging current (for example, the charging current is 2 A). At the same time, there are some charging adapters with which a charging with bigger current can be performed stably. However, although the charging time is reduced to some extents, the constant current charging with bigger current can bring safety risks. For example, the cell and charging circuit in the mobile terminal can be damaged or even a fire is caused due to the continuous charging with bigger current, if the charging adapter is not disconnected from the mobile terminal in time when electric quantity in the cell is full.